Microemulsion foaming agent for improving recovery efficiency of high-temperature heavy oil reservoir as well as preparation method and application of microemulsion foaming agent

Abstract

The invention provides a microemulsion foaming agent for improving the recovery ratio of a high-temperature heavy oil reservoir as well as a preparation method and application of the microemulsion foaming agent. The microemulsion foaming agent comprises the following components in parts by mass: 1 part of a fatty amine polyoxyethylene ether anionic surfactant, 1-50 parts of a sulfonate surfactant, 1-50 parts of a surfactant, and 1-50 parts of a surfactant. And 1-50 parts by mass of a zwitterionic surfactant. The obtained microemulsion foaming agent can be applied to an oil displacement process of a high-temperature heavy oil reservoir, solves the technical problem of simultaneously meeting the requirements of viscosity reduction, profile control and channeling sealing of heavy oil, and can improve the crude oil recovery rate of the heavy oil reservoir.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas exploitation, and further relates to a microemulsion foam agent for improving the recovery ratio of high-temperature heavy oil reservoirs, a preparation method and application thereof. BACKGROUND

[0002] In recent years, the dependence of China's crude oil imports on foreign countries has been increasing year by year, and has exceeded the energy security red line of 70%, so it is urgent to increase domestic crude oil production. At present, the heavy oil reserves in China exceed 1.9 billion tons, but the recovery ratio is insufficient, often less than 15%. Therefore, various enhanced oil recovery methods have been used in heavy oil exploitation, such as thermal recovery technology, chemical flooding technology, foam flooding technology, etc., but the oil displacement effect is still not ideal. This is because a single enhanced oil recovery method can only solve one aspect of the problem, while the exploitation of heavy oil is limited by multiple factors. For example, thermal recovery technology and chemical flooding technology can reduce the viscosity of heavy oil by injecting high-temperature steam and viscosity reducer respectively, but ignore profile control and channeling control, resulting in the channeling of injected steam and viscosity reducer from the high-permeability area of the reservoir, and not fully contacting the heavy oil for viscosity reduction. For example, foam flooding technology is used to profile control and channeling control by injecting foam, but cannot effectively reduce the viscosity of heavy oil, resulting in low oil displacement efficiency. Even if the above technologies are used in combination, the incompatibility of chemical agents often leads to low oil recovery. For example, chemical flooding and foam flooding technologies are often used in combination, usually by first injecting foam for profile control and channeling control, and then injecting viscosity reducer for viscosity reduction and oil washing. However, the foam agent and the viscosity reducer will interfere with each other, resulting in unstable foam, reduced profile control and plugging efficiency, and reduced viscosity reduction and oil washing rate. In addition, the viscosity reducer cannot enter the area blocked by the foam, resulting in a large amount of residual heavy oil in this area that cannot be effectively displaced. Therefore, in order to effectively improve the recovery ratio of heavy oil, it is necessary to reduce the viscosity of heavy oil while profile controlling and plugging the reservoir to ensure that the chemical agent can fully spread to the heavy oil area. However, the existing viscosity reducer, microemulsion agent or foam agent can only solve a single factor and cannot meet the requirements of viscosity reduction and oil washing and profile control and channeling control at the same time.

[0003] Therefore, it is necessary to invent a new chemical agent that can simultaneously reduce the viscosity of heavy oil and improve the plugging efficiency of foam. SUMMARY

[0004] In order to solve the technical problems existing in the prior art, the present application provides a microemulsion foam agent for improving the recovery ratio of high-temperature heavy oil reservoirs, a preparation method and application thereof.

[0005] The molecule thermal motion of the existing foam agent is improved at high temperature, which leads to the decrease of the surface concentration of the foam agent and the poor foam performance; and the existing foam agent cannot effectively reduce the viscosity of the thickened oil, which leads to the low oil washing efficiency and finally cannot effectively improve the recovery rate of the high-temperature thickened oil reservoir.

[0006] The present application adopts a certain proportion of a fatty amine polyoxyethylene ether anionic surfactant, a sulfonate surfactant and a zwitterionic surfactant. The fatty amine polyoxyethylene ether anionic surfactant has a double-branch structure and can cover a larger gas-liquid interface. The amine group contained therein has a strong electrostatic attraction with the anion group in the sulfonate surfactant and the zwitterionic surfactant, which can offset the negative effects caused by the molecule thermal motion and further increase the coverage concentration at the gas-liquid interface, thereby effectively improving the stability of the foam at high temperature. The amine group in the fatty amine polyoxyethylene ether anionic surfactant and the cationic group in the zwitterionic surfactant both have a strong interaction with the anionic polar substances such as asphalt and colloid in the thickened oil, which can enter the asphalt and colloid and effectively break the viscous components in the thickened oil to reduce the viscosity of the thickened oil. The oil-in-water lower phase microemulsion generated can disperse the crude oil in the water phase, further reduce the viscosity of the thickened oil and enhance the oil washing capacity of the formula.

[0007] The three surfactants used in the present application have a synergistic effect after compounding, and the prepared microemulsion foam agent can break the tight structure of the asphalt and colloid in the thickened oil and generate oil-water lower phase microemulsion with the thickened oil to reduce the viscosity of the crude oil and increase the oil washing efficiency; at the same time, it can be mixed with gas to generate foam for profile control and channeling sealing, thereby increasing the chemical agent sweep range and finally realizing the thickened oil viscosity reduction and profile control and channeling sealing simultaneously by using one chemical agent and its supporting technology.

[0008] One of the purposes of the present application is to provide a microemulsion foam agent for improving the recovery rate of a high-temperature thickened oil reservoir.

[0009] The microemulsion foam agent comprises the following components in 1 mass part of the fatty amine polyoxyethylene ether anionic surfactant:

[0010] 1 mass part of the fatty amine polyoxyethylene ether anionic surfactant;

[0011] 1-50 mass parts of the sulfonate surfactant; preferably 1-20 mass parts; more preferably 2-15 mass parts;

[0012] 1-50 mass parts of the zwitterionic surfactant; preferably 1-20 mass parts; more preferably 2-4 mass parts.

[0013] When the amount of the fatty amine polyoxyethylene ether anionic surfactant is 1 part by mass, the preferred amount of the sulfonate surfactant is, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts by mass, or any range defined by any two of the above values, for example, 8 to 15 parts by mass, and so on; and the preferred amount of the zwitterionic surfactant is, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 parts by mass, or any range defined by any two of the above values, for example, 2 to 4 parts by mass, and so on.

[0014] In a preferred embodiment of the present application,

[0015] Optionally, the microemulsion foam agent further comprises water, and the amount of the water can be any part by mass, preferably 1 to 99.9 parts by mass, and more preferably 20 to 80 parts by mass.

[0016] More preferably, the amount of the water is, for example, 20, 30, 40, 50, 60, 70, 80 parts by mass, or any range defined by any two of the above values, for example, 20 to 40 parts by mass, and so on.

[0017] In a preferred embodiment of the present application,

[0018] The fatty amine polyoxyethylene ether anionic surfactant has the following structural formula:

[0019]

[0020] In the formula, R1 is an alkyl group having 8 to 18 carbon atoms, preferably an alkyl group having 8 to 16 carbon atoms; m+n is any integer from 1 to 40, preferably any integer from 2 to 25; X is -COO- (carboxyl group) or -SO3- M (sulfonic acid group); and M is any one of an alkali metal and an ammonium group, and the alkali metal is more preferably any one of sodium and potassium. 40 30 - -

[0021] The carboxylate in the fatty amine polyoxyethylene ether anionic surfactant is the fatty amine polyoxyethylene ether carboxylate in Chinese Invention Patent CN103421174A (Invention Title: Fatty amine polyoxyethylene ether carboxylate and preparation method thereof), and the sulfonate is the fatty amine polyoxyethylene ether sulfonate in Chinese Invention Patent CN109679615A (Invention Title: Method for using foam drainage agent composition to drain and produce gas in ultra-deep gas well).

[0022] In a preferred embodiment of the present application,

[0023] The sulfonate surfactant has the following structural formula:

[0024] ​​​​

[0025] wherein R 2 is C 4 -C 30 alkyl, preferably C 5 -C 25 alkyl; R 3 is vinyl (-CHCH-) or hydroxyethyl (-CH(OH)CH2-); Y is H or C 12 alkyl, preferably H or C 10 alkyl; K is any one of alkali metal, more preferably any one of sodium or potassium.

[0026] In a preferred embodiment of the present application,

[0027] the structure of the zwitterionic surfactant is:

[0028]

[0029] wherein R4 is C 37 alkyl or alkenyl, preferably C 30 alkyl or alkenyl; y is 0 or 1; when y is 0, no amide group is included; when y is 1, one amide group is included; Z is any one of carboxylic acid group (-CO2 - ), alkyl sulfonic acid group (-CH2CH2SO3 - ), and alkyl hydroxyl sulfonic acid group (-CH(OH)CH2SO3 - ).

[0030] The second object of the present application is to provide a preparation method of microemulsion foam for improving the recovery rate of high-temperature heavy oil reservoir, comprising the following steps:

[0031] The raw materials including fatty amine polyoxyethylene ether anionic surfactant, sulfonate surfactant and zwitterionic surfactant are mixed to obtain the microemulsion foam;

[0032] Preferably,

[0033] The viscous liquid raw materials are heated to 50-80℃ before being added and mixed, and the solid raw materials are crushed before being added and mixed; and / or,

[0034] The mixing temperature is 50-80℃, and the mixing time is 5-10 hours, and the mixing is uniform under stirring.

[0035] The third object of the present application is to provide an application of the above-mentioned microemulsion foam for improving the recovery rate of high-temperature heavy oil reservoir in the oil displacement process of high-temperature heavy oil reservoir;

[0036] Preferably, the microemulsion foam agent is diluted with water into a microemulsion foam solution and injected into the high-temperature heavy oil reservoir; the active substance content in the microemulsion foam solution is preferably 0.01% to 10%, more preferably 0.1% to 5%.

[0037] In a preferred embodiment of the present application,

[0038] The formation temperature of the high-temperature heavy oil reservoir is 70 to 160°C, the heavy oil viscosity is 100 to 100000 mPa·s, and the formation water salinity is 0 to 50000 mg / L; more preferably, the heavy oil viscosity is 2000 to 20000 mPa·s.

[0039] The oil displacement process comprises injection of the microemulsion foam solution, injection of non-condensable gas, optional water, and optional steam injection; preferably, the non-condensable gas comprises at least one of nitrogen, methane, natural gas, and air, more preferably at least one of nitrogen, methane, and natural gas; the water is preferably brine.

[0040] In a preferred embodiment of the present application,

[0041] In the oil displacement process, the microemulsion foam solution is injected alone or in combination with one or more of non-condensable gas, steam, or water; and / or,

[0042] The microemulsion foam solution slug is injected before, in, or after the slug of one or more of non-condensable gas, steam, or water.

[0043] In a preferred embodiment of the present application,

[0044] The microemulsion foam agent generates an oil-water sub-phase microemulsion during heavy oil displacement.

[0045] The microemulsion foam agent generates a stable strong foam during heavy oil displacement, and the foam strength is quantitatively described by apparent viscosity, with a foam strength of 5 to 5000 mPa·s, preferably 20 to 2000 mPa·s.

[0046] Compared with the prior art, the present application has the following beneficial effects:

[0047] The present application solves the problem that in the development of existing high-temperature heavy oil reservoirs, a chemical agent and its supporting technology cannot be used to simultaneously satisfy the viscosity reduction and profile control and channeling sealing of heavy oil. The molecular thermal motion of existing foam agents is increased at high temperatures, resulting in a decrease in the surface concentration of the foam agent and a deterioration of the foam performance; moreover, the existing foam agents cannot effectively reduce the viscosity of heavy oil, resulting in low oil washing efficiency and ultimately failing to effectively improve the recovery of high-temperature heavy oil.

[0048] The fatty amine polyoxyethylene ether anionic surfactant has a double-branch structure, can cover a larger gas-liquid interface, has strong electrostatic attraction with anion groups in sulfonate surfactants and zwitterionic surfactants, can offset the negative effects caused by molecular thermal motion, further increases the coverage concentration at the gas-liquid interface, and thus effectively improves the stability of the foam at high temperature. The amine groups in the fatty amine polyoxyethylene ether anionic surfactant and the cationic groups in the zwitterionic surfactant have strong interaction with anionic polar substances such as asphalt and colloid in thick oil, can enter the asphalt and colloid, effectively break the viscous components in the thick oil, and reduce the viscosity of the thick oil. Moreover, the oil-in-water lower-phase microemulsion generated can disperse the crude oil in the water phase, further reduce the viscosity of the thick oil, and enhance the oil washing capacity of the formula.

[0049] Compared with the middle-phase and upper-phase microemulsions, the formation of the lower-phase microemulsion proves that the surfactants still exist in the water phase, thus ensuring that there is sufficient surfactant in the water phase to stabilize the foam. Therefore, the microemulsion foam agent can break the compact structure of asphalt and colloid in the thick oil, and generate an oil-water lower-phase microemulsion with the thick oil, so as to reduce the viscosity of the crude oil and increase the oil washing efficiency; meanwhile, the microemulsion foam agent can be mixed with gas to generate foam for profile control and channeling sealing, so as to increase the chemical agent sweeping range, and finally realize the thick oil viscosity reduction and profile control and channeling sealing simultaneously by using one chemical agent and its supporting technology. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 A comparison chart of the dissolution of the microemulsion foam agent MF1 (effective concentration 1%) prepared in Example 1 and alpha sodium olefin sulfonate in 50,000 mg / L brine at 20-160℃;

[0051] Figure 2 A comparison chart of the oil-water phase state of the microemulsion foam agent MF1 (effective concentration 0.3%) prepared in Example 1 and C14-20 alpha sodium olefin sulfonate;

[0052] In which, the left side is C14-20 alpha sodium olefin sulfonate, and the right side is MF1;

[0053] Figure 3 A foam apparent viscosity curve chart of the microemulsion foam agent MF1 (effective concentration 0.3%) MF1 prepared in Example 1 and nitrogen displacement;

[0054] Figure 4 A chart of the change of the apparent viscosity of the foam of the microemulsion foam agent MF2 (effective concentration 1%) prepared in Example 2 and nitrogen displacement with the injection pore volume (PV);

[0055] Figure 5Fig. 1 is a graph showing the apparent viscosity of the foam prepared from the microemulsion foam agent MF1 prepared in Example 1, nitrogen, and steam-displaced foam as a function of the injected pore volume (PV);

[0056] Figure 6 Fig. 1 is a graph showing the apparent viscosity of the foam prepared from the microemulsion foam agent MF1 prepared in Example 1, nitrogen, and steam-displaced foam as a function of the injected pore volume (PV); DETAILED DESCRIPTION

[0057] The following specific description of the application is made in conjunction with the specific drawings and examples. It is necessary to point out that the following examples are only used to further illustrate the application and cannot be understood as limiting the scope of protection of the application. Some non-essential improvements and adjustments to the application made by those skilled in the art based on the content of the application are still within the scope of protection of the application.

[0058] The raw materials used in the examples and comparative examples, if not specifically limited, are disclosed in the prior art, for example, can be directly purchased or prepared according to the preparation method disclosed in the prior art.

[0059] C 14 ~C 20 Sodium fatty amine polyoxyethylene ether carboxylate (EO 6) of alkyl group, C8-C 14 Ammonium fatty amine polyoxyethylene ether carboxylate (EO 2) of alkyl group is prepared according to Chinese invention patent CN103421174A (invention title: “Fatty amine polyoxyethylene ether carboxylate and its preparation method”);

[0060] C 16 -C 24 Potassium fatty amine polyoxyethylene ether sulfonate (EO 10) of alkyl group, C8-C 20 -C 30 Potassium fatty amine polyoxyethylene ether sulfonate (EO 25) of alkyl group is prepared according to Chinese invention patent CN109679615A (invention title: “Method for using foam drainage agent composition to drain and produce gas in ultra-deep gas well”);

[0061] C 14 -C 20 Sodium alpha olefin sulfonate of alkyl group, C8-C 14 Sodium internal olefin sulfonate of alkyl group, C5-C 13 Ammonium hydroxysulfonate of alkyl group, C 15 -C 25 Sodium hydroxysulfonate of alkyl group is prepared according to the literature “Preparation and analysis method of sodium alpha-olefin sulfonate” (Liu Xiaochen, Jan Jianwei, et al., 2019, China Detergent Industry, No. 2, pp. 61-67);

[0062] C 14 -C20 alkyl carboxybetaine, C 16 -C 24 olefinic amamidopropyl hydroxysulfonate betaine, C7-C 13 alkyl propyl sulfonyl betaine, C 20 -C 30 The olefin-based amide carboxylated betaine was prepared according to the literature "Research Progress on Synthesis Process of Betaine Surfactant" (Wang Wenquan, Liu Yizhang, Meng Yuan, 2020, China Detergent Industry, No. 10, pp. 71-77) and "Preparation and Performance Comparison of Alkyl Betaine" (Xiang Bin, Zhang Qunhui, 1995, Journal of Zhejiang University of Technology, No. 2, pp. 125-129).

[0063] Test method:

[0064] Viscosity test: The viscosity of the liquid was measured at 50°C using a HAAKE viscometer (model: Viscotester IQ).

[0065] Oil-water phase testing at 70–160℃: At 70–100℃, 3 ml of aqueous solution and 1 ml of crude oil are placed in a glass tube, heated to the test temperature using a metal bath, and then the oil-water phase is mixed by shaking. After repeating the shaking three times, the mixture is left to stand at the test temperature for one day, and the oil-water phase is observed. Oil-water phase testing at 110–160℃: 3 ml of aqueous solution and 1 ml of crude oil are placed in a full-viewing-window reactor, which is rotated and stirred at the specified temperature for 1 hour, and then left to stand for one day, and the oil-water phase is observed.

[0066] Measurement of viscosity of heavy oil after viscosity reduction: 100g of heavy oil and 100g of aqueous solution were placed in a sealed container and mixed by shaking at 70℃ for 1 hour. After standing overnight in an oven at 70-160℃, the mixture was removed and cooled to room temperature, and the viscosity of the upper oil phase was measured.

[0067] Physical simulation experiments at different temperatures (120℃, 150℃): Reference, Cui, et al., 2020, Surfactant Formulation for Foam Mobility Control and Gas Shut-Off in Harsh Operational and Reservoir Conditions, SPE-203481-MS.

[0068] Foam strength testing: Same as physical simulation experiment;

[0069] Apparent viscosity as a function of injection orifice volume (PV): Same as physical simulation experiment;

[0070] Heavy oil recovery rate: Same as physical simulation experiment.

[0071] The purity mentioned in the examples refers to the mass concentration of the aqueous solution.

[0072] Example 1

[0073] Preparation and application of microemulsion foaming agent MF1.

[0074] The fatty amine polyoxyethylene ether anionic surfactant used in MF1 is sodium fatty amine polyoxyethylene ether carboxylate, with the following structural formula:

[0075]

[0076] Where X is a carboxylic acid group, M is a sodium ion, and R1 is a C ion. 14 -C 20 The total number of alkyl groups and polyethers, m+n, is 6;

[0077] The sulfonate surfactant used is sodium alpha olefin sulfonate, with the following structural formula:

[0078]

[0079] Where R2 is C 14 -C 20 Alkyl group, R3 is vinyl group, Y is H group, and K is sodium ion;

[0080] The zwitterionic surfactant used is carboxybetaine, with the following structural formula:

[0081]

[0082] Z - It is a carboxylic acid group, and R4 is a carbon atom. 14 -C 20 Alkyl groups, where y is 0.

[0083] 450 kg of the above-mentioned sodium alpha olefin sulfonate (purity 35%), 50 kg of the above-mentioned sodium fatty amine polyoxyethylene ether carboxylate (purity 32%), and 84 kg of the above-mentioned carboxybetaine (purity 50%) were sequentially added to a reaction vessel. After the reaction vessel was heated to 60°C, it was stirred for 6 hours to obtain a homogeneous solution, namely microemulsion foam agent MF1.

[0084] The obtained microemulsion foaming agent MF1 was prepared into a solution with an effective concentration of 1 wt%, and dissolved in 50,000 mg / L saline solution at 20–160 °C. Figure 1 As shown. By Figure 1 It is known that MF1 is soluble in 50,000 mg / L saline solution, but the sodium alpha olefin sulfonate used in MF1 is not soluble in 50,000 mg / L saline solution.

[0085] The obtained microemulsion foaming agent MF1 was formulated to an effective concentration of 0.3 wt%. It can emulsify heavy oil with a viscosity of 5000 mPa·s in 50000 mg / L brine at 70–160 °C, producing a stable oil-water lower phase microemulsion. Figure 2 As shown, the viscosity of crude oil was reduced to 24 mPa·s.

[0086] In a physical simulation experiment at 120℃, the core sample saturated with heavy oil was first displaced with 2 PV (pore volume) brine, followed by simultaneous injection of 0.3 wt% MF1 solution and nitrogen gas. Strong foaming was generated during the displacement process using the microemulsion foaming agent and nitrogen gas. Figure 3 The apparent viscosity in foam is a quantitative description of foam strength. Figure 3 The graph shows the apparent viscosity of MF1 and nitrogen foam as a function of injection orifice volume (PV). Heavy oil recovery was calculated by measuring the oil content in the effluent, increasing the recovery rate from 34% with brine flooding (injecting brine instead of foam) to 55%.

[0087] Example 2

[0088] Preparation and application of microemulsion foaming agent MF2.

[0089] The fatty amine polyoxyethylene ether anionic surfactant used in MF2 is potassium fatty amine polyoxyethylene ether sulfonate, with the same general structural formula as in Example 1, wherein X is a sulfonic acid group and alkyl R1 is C 16 -C 24 The total number of alkyl groups and polyethers (m+n) is 10, and M represents potassium ions; the sulfonate surfactant used is sodium sulfonate with the same general structural formula as in Example 1, wherein R2 is C8-C. 14 Alkyl group, R3 is vinyl group, Y is C6-C. 10 The carbon chain, K being a sodium ion; the zwitterionic surfactant used is amamidopropyl hydroxysulfonyl betaine, with the same general structural formula as in Example 1, wherein Z... - It is an alkyl hydroxysulfonic acid group (-CH(OH)CH2SO3) - The carbon chain R4 is C 16 -C 24 The olefinic group, y is 1.

[0090] 700 kg of the above-mentioned sodium olefin sulfonate (30% purity), 64 kg of the above-mentioned fatty amine polyoxyethylene ether sulfonate (25% purity), and 120 kg of the above-mentioned amamidopropyl hydroxysulfonate betaine (40% purity) were heated to 80°C and then added sequentially to a reaction vessel. After the reaction vessel was heated to 80°C, it was stirred for 6 hours to obtain a homogeneous solution, namely the microemulsion foam agent MF2.

[0091] The obtained microemulsion foam MF2 was prepared into a 1 wt% effective concentration solution, which was dissolved in 35000 mg / L brine at 20-160°C. In 35000 mg / L brine at 70-160°C, the stable oil-water lower phase microemulsion was generated for the thick oil with an emulsified viscosity of 23000 mPa-s, and the crude oil viscosity was reduced to 52 mPa-s.

[0092] In a physical simulation displacement experiment at 150°C, the core saturated with thick oil was first displaced by 2 PV (pore volume) brine, and then was alternately injected with 1 wt% effective concentration MF2 solution and nitrogen for displacement, the MF2 and nitrogen slug were 0.2 PV and 0.5 PV respectively, and finally the MF2 and nitrogen were simultaneously injected, as shown in Figure 4 The thick oil recovery rate was calculated by measuring the oil content in the effluent, and the thick oil recovery rate was increased from 28% at the time of brine displacement to 43%.

[0093] Example 3

[0094] The preparation and application of the microemulsion foam MF3 were different from those of Example 1 as follows:

[0095] The fatty amine polyoxyethylene ether anionic surfactant used was fatty amine polyoxyethylene ether ammonium carboxylate, the general structure of which was the same as that of Example 1, wherein X was a carboxyl group, R1 was C8-C 14 alkyl, the total number of polyethers m+n was 2, and M was an ammonium ion; the sulfonate surfactant used was alkyl hydroxyl ammonium sulfonate, the general structure of which was the same as that of Example 1, wherein R2 was C5-C 13 alkyl, R3 was a hydroxyethyl group, Y was H, and K was an ammonium ion; the zwitterionic surfactant used was alkyl propyl sulfobetaine, the general structure of which was the same as that of Example 1, Z - was an alkyl sulfonic acid group (-CH2CH2SO3 - ), the carbon chain R4 was C7-C 13 alkyl, and y was 0.

[0096] Except for the above differences, the other conditions of Example 3 were the same as those of Example 1, and the microemulsion foam MF3 was obtained.

[0097] MF3 could be dissolved in 50000 mg / L brine at 20-160°C. In 50000 mg / L brine at 70-160°C, the stable oil-water lower phase microemulsion was generated for the thick oil with an emulsified viscosity of 5000 mPa-s, and the crude oil viscosity was reduced to 31 mPa-s.

[0098] Under the same physical model displacement as Example 1, the thick oil recovery rate was increased from 36% at the time of brine displacement to 48%.

[0099] Example 4

[0100] The preparation and application of the microemulsion foam MF4 is different from that of Example 2 in that:

[0101] The fatty amine polyoxyethylene ether anionic surfactant used is potassium fatty amine polyoxyethylene ether sulfonate, with the general structure as in Example 1, wherein X is a sulfonate group, R1 is C 20 -C 30 alkyl, the total number of polyether m+n is 25; the sulfonate surfactant used is sodium alkyl hydroxyl sulfonate, with the general structure as in Example 1, wherein R2 is C 15 -C 25 alkyl, R3 is hydroxyethyl, and Y is C2-C5 alkyl; the zwitterionic surfactant used is amido carboxy betaine, with the general structure as in Example 1, wherein Z - is a carboxylic acid group (-CO2 - ), the carbon chain R4 is C 20 -C 30 alkylene group, and y is 1.

[0102] Except for the above differences, the other conditions of Example 4 are the same as those of Example 2, and the microemulsion foam MF4 is obtained.

[0103] MF4 can be dissolved in 20,000 mg / L brine at 20-160°C. In 70-160°C, 20,000 mg / L brine, the emulsified viscosity of the thick oil is 23,000 mPa-s, and a stable oil-water lower phase microemulsion is produced, reducing the viscosity of the thick oil to 89 mPa-s.

[0104] Under the same displacement of the physical model as in Example 2, the recovery of the thick oil is increased from 30% in brine displacement to 39%.

[0105] Example 5

[0106] The difference from Example 1 is that methane is used instead of nitrogen for displacement.

[0107] Except for the above difference, the microemulsion foam and its application of Example 5 are the same as those of Example 1. The apparent viscosity of the foam and the recovery have no substantial effect.

[0108] Example 6

[0109] The difference from Example 1 is that steam is injected into the saturated thick oil core instead of brine.

[0110] Except for the above difference, the microemulsion foam and its application of Example 6 are the same as those of Example 1. The apparent viscosity of the foam has no substantial effect, and the recovery of the thick oil is increased from 50% in steam displacement to 69%.

[0111] Example 7

[0112] The difference from Example 6 is that MF1, nitrogen and steam are injected into the core after steam flooding instead of MF1 + nitrogen slug;

[0113] In addition to the above differences, the microemulsion foam agent of Example 7 and its application are the same as Example 6. The apparent viscosity of the foam decreases as shown in Figure 5 The heavy oil recovery rate is increased from 50% during steam flooding to 76%.

[0114] Comparative Example 1

[0115] The low-tension foam agent ZY-1 prepared in Example 1 of Chinese invention patent CN106590607A (invention title: "temperature-resistant and salt-resistant low-tension foam agent composition and its preparation method") is used to perform the test in Example 1.

[0116] 1wt% effective concentration of ZY-1 can be dissolved in 0-50000mg / L brine at 20-160℃.

[0117] At 70-160℃ and 50000mg / L brine, 0.3wt% effective concentration of ZY-1 can reach low oil-water interfacial tension (10 -3 mN / m) with 5000mPa·s heavy oil, but oil-water middle phase microemulsion is generated. This causes surfactant to exist in the middle phase microemulsion, and the surfactant content in the lower aqueous phase is insufficient to maintain stable foam. Therefore, under the same displacement of the physical model, strong foam cannot be generated, and the foam strength is shown in Figure 6 The heavy oil recovery rate is not substantially increased. If the brine salinity is reduced, although the oil-water middle phase microemulsion can be broken, the foam agent returns to the aqueous phase, but the oil-water interfacial tension is increased, which does not meet the definition of the low-tension foam agent in the patent, and stable oil-water lower phase microemulsion cannot be generated, and the heavy oil viscosity is not significantly reduced. Therefore, the foam agent ZY-1 is not suitable for such high-temperature heavy oil reservoirs.

[0118] The microemulsion foam agents prepared in Examples 1-7 can break the tight structure of asphalt and colloid in heavy oil, and generate oil-water lower phase microemulsion with heavy oil to reduce the viscosity of crude oil and increase the oil washing efficiency; at the same time, the foam agent can be mixed with gas to generate foam for profile control and channel sealing, thereby increasing the chemical agent sweep range, and finally using one chemical agent and its supporting technology to simultaneously achieve heavy oil viscosity reduction and profile control and channel sealing.

Claims

1. A microemulsion foam, comprising the following components by 1 part of fatty amine polyoxyethylene ether anionic surfactant: fatty amine polyoxyethylene ether anionic surfactant 1 part by mass; sulfonate surfactant 1-50 parts by mass; preferably 1-20 parts by mass; more preferably 2-15 parts by mass; zwitterionic surfactant 1-50 parts by mass; preferably 1-20 parts by mass; more preferably 2-15 parts by mass.

2. The microemulsion foam according to claim 1, wherein: the microemulsion foam further comprises water, preferably in an amount of 1-99.9 parts by mass, more preferably 20-80 parts by mass.

3. The microemulsion foam according to claim 1, wherein: the fatty amine polyoxyethylene ether anionic surfactant has the following structure:

4. The microemulsion foam according to claim 1, wherein: the sulfonate surfactant has the following structure:

5. The microemulsion foam according to claim 1, wherein: the zwitterionic surfactant has the following structure: Where R1 is C8~C 40 Alkyl groups, preferably C8-C9 30 Alkyl group; m+n is any integer from 1 to 40, preferably any integer from 2 to 25; X is -COO - or -SO3 - M is any one of alkali metal and ammonium group; more preferably, the alkali metal is any one of sodium and potassium.

6. A method for preparing the microemulsion foam according to any one of claims 1-5, comprising the following steps: mixing raw materials including fatty amine polyoxyethylene ether anionic surfactant, sulfonate surfactant and zwitterionic surfactant to obtain the microemulsion foam; Where R2 is C4~C 30 Alkyl groups, preferably C5-C6 25 alkyl; R3 is vinyl or hydroxyethyl; Y is H or C1-C 12 Alkyl groups, preferably H or C2-C2. 10 The alkyl group; K is any one of alkali metal and ammonium group, wherein the alkali metal is more preferably any one of sodium and potassium. preferably, heating viscous liquid raw materials to 50-80°C before adding, and adding after crushing solid raw materials; and / or, wherein R4 is a C5 to C20 alkyl or alkenyl group, preferably a C7 to C12 alkyl or alkenyl group; R5 is a C1 to C20 alkyl or alkenyl group, preferably a C1 to C6 alkyl or alkenyl group; and R6 is a C1 to C20 alkyl or alkenyl group, preferably a C1 to C6 alkyl or alkenyl group. 37 wherein R4 is a C5 to C20 alkyl or alkenyl group, preferably a C7 to C12 alkyl or alkenyl group; R5 is a C1 to C20 alkyl or alkenyl group, preferably a C1 to C6 alkyl or alkenyl group; and R6 is a C1 to C20 alkyl or alkenyl group, preferably a C1 to C6 alkyl or alkenyl group. 30 wherein R4 is a C5 to C20 alkyl or alkenyl group, preferably a C7 to C12 alkyl or alkenyl group; R5 is a C1 mixing at a temperature of 50-80°C for 5-10 hours under stirring until uniform.

7. Use of the microemulsion foam according to any one of claims 1-5 or prepared by the method according to claim 6 in a high-temperature viscous oil reservoir oil displacement process; preferably, the microemulsion foam is diluted with water to form a microemulsion foam solution, which is injected into a high-temperature viscous oil reservoir; preferably, the active substance content in the microemulsion foam solution is 0.01%-10%, more preferably 0.1%-5%.

8. The use according to claim 7, wherein: the high-temperature viscous oil reservoir has a formation temperature of 70-160°C, a viscous oil viscosity of 100-100000 mPa·s, and a formation water salinity of 0-50000 mg / L; and / or, the oil displacement process comprises injection of the microemulsion foam solution, injection of non-condensable gas, optional injection of water, and optional injection of steam; preferably, the non-condensable gas comprises at least one of nitrogen, methane, natural gas, and air, more preferably at least one of nitrogen, methane, and natural gas; and / or, the water is preferably brine.

9. The use according to claim 8, wherein: in the oil displacement process, the microemulsion foam solution is injected alone or in combination with one or more of non-condensable gas, steam, or water; and / or, the microemulsion foam solution slug is injected before, in, or after a slug of one or more of non-condensable gas, steam, or water.

10. The use according to any one of claims 7-9, wherein: ​ ​ ​ ​ ​ ​ ​ ​ The microemulsion foam generates an oil-water sub-phase microemulsion during the heavy oil displacement process; and / or, The microemulsion foam generates a stable strong foam during the heavy oil displacement process, and the foam strength is quantitatively expressed by the apparent viscosity, which is 5-5000 mPa·s, preferably 20-2000 mPa·s.

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